Key-hole guard



March 3, 1931. J Q SHERMAN 1,794,481

KEY HOLE GUARD Filed March 15, 192 2 Sheets-Sheet 1 8% a. SM INVENTOR.

W ATTORNEYS.

March 3, i931. J SHERMAN 7 1,794,481

KEY HOLE GUARD Filed March 1.926 2 Sheets-Sheet 2 INVENTOR.

A TTORNEYS.

Patented Mar. 3, 1931 JOHN Q. SHERMAN, or DAYTON, onroj KEY-HOLE queen Application filed March 15, 1926; seal-No. 94,2512.

My invention relates to guards for insertion into the key holes of ordinary door locks and the like, from one side thereof in order to prevent the insertion of a key from the other side, and opening the lock.

There have been in the past various forms advocated for such a-purpose, but so far as I am advised these have been uniformly cone structed so as to co-operate with the tumblers 1 of the lock, or actually take the place of a Q key. These old advocated forms have never come into use because of their complication and because they were not adaptable for use with a wide variety of locks.

' My novel devices are adapted for use with any lock having a key hole plate available from both sides through the familiar key hole, formed with an opening terminating at one end in a hole, or else formed with a key slot having plain walls through which anarrow metal plate can be inserted.

It is my object to clamp or grip a piece of metal in such a position that it cannot be dislodged from the key hole, said metal projecting into the path of any instrument inserted for the purpose of operating the look from without, or dislodging the key itself, followed by an unauthorized operation of the lock.-

It is my object to provide as simple as possible a device, which among other things'can be packed in a small neat box with other auxiliary devices, and can be operated by following simple directions.

I accomplish my objects by that certain construction and arrangement of parts to be hereinafter more specifically pointed out and claimed.

In the drawing:

Figure 1 is a perspective view showlng my preferred form of device prior to msert-lon in the key hole.

Figure '2 is a like view showing the device inserted and clamped in place. Y

Figure 3 is an elevation of a door with parts broken away to show my preferred form of guard, as applied.

Figure 4 is a detail of the guard, without the clamp nut, showing a plan view thereof, as applied.

-Figure 5 is-a detailof the clampnut.

Figure6is a side elevation partly brokenaway of a modified form of guard.

Figure 7 is a plan View thereof. Figure 8 is a broken section of a door lock, 55.. showing another modified form.

Figure-9 is aperspective of a form'of de-' I ICIGItO be applied when the key is left in the 0C Figure 10 is a side elevation showing the l 6 method of use of the form shown in Figure 9. Figure 11 is another form of device to be appliecl' directly' tothe key and serving to prevent dislodgment thereof.

I have showna lock casing plate 1, with a key hole 2. The device itself isformed as a bar offiat metal 3, having a pair-of ears 4, 4, which project laterally intermediate its ends. A round portion of the bar is threaded as at 5, and a clamp nut 6 is provided to fit the threads, this nut having preferably a I conical tip 7 anda knurled double rim 8, for easymanipulation bythe'fingers; In use the flat'tip is inserted into the key hole sothat theinserted portion lies in the pa'ssageway through which a key 8a would be inserted from the other side of the door. The bar is revolved to bring the two ears into a crosswise position illustrated in plan in Figure 4, and; in elevation in Figure 3, so that the bar, cannot be dislodged by pushing it inwardly from the outside of the door. The nutflis then screwed down tightly against the inner face of the lock plate, thereby holding the device in a clamped position, and entirely free of any danger of being dislodged from without the door.

The tip of the bar does not project out through the other side of the lock plate, but terminates within the lock plate so that a tool could not be applied to twist it 01f, and it will be impossible to use a master key, or a dupli'cate'key from the outside of the door to bring about an opening thereof.

In Figure 6 and Figure 7 I have shown a device which operates by a wedging action instead of by a screw clamp action. The shank ofthe device is made by two spring metal plates 10,10, provided with a knurled head 11. At the inner end they are connected by a pin 12 and a pin 13, passing through the two plates mounts a trigger wedge 14.. The sides of the plates are turned out at 15 to provide a means to hook inside of the door plate. In use the device is placed inside of the key hole, by compressing the plates.

The wedge is then pushed down. at the inner end to get the hooks which have been snapped inside of the lock plate, well spread, and likewise spreading the two bars in the key hole slot. This clamps the plug formed by the two plates, Within the lock plate,'and prevents insertion of a key by an unauthor ized person.

A similar device maybe formed of a rod 20, on which are riveted two thin spring plates 21, connected. loosely at their inner ends b a in 22 havin a double head which passes through the rod. The, ends; of the springs are hookedat 23,. and-the. pin and the hooks act to gripthe devicein the key hole plate. The plates are compressed at the inner end to allow for the entry of the flange 31,- is dropped over, the key, with. the

' ro'ection 32 extendin into the strai ht P J z:

part of the slot. The screw 33 in the overhanging flange is then turned down to clamp the device on the shank of the key. The projection 32 prevents the key from being dislodged, since it cannot be revolvedaway from locking position, due to the presence of. the projection in the straight part of the key hole slot.

i Figure 11. is shown a spring, which win:

serveto accomplish the same object. as the device in. Figure 9.

. A spring 40' is set over the shank of the key and screwed onto the shank. It then bears against the head of the key and against.

the tumbler'actuating leaf. WVhen the key is inserted, the spring catches on the key hole and compresses against the head or handle, thus holding the key tight in the lock plate when ithas been turned to lock the door.

Havingthus described my invention, what I claim as new and desire to secure by Letters Patent, is

An attachment for a key to prevent the turning thereof within a lock subsequent to the insertion otthe key within the lock, comprisin a sheet metal; member having a return bent flange to laterally engage the shank of the keyfrom above, said member The stud prevents having a protruding portion adapted to be received within the key hole slot and prevent turning of said member, and means to clamp said member to the key.

JOHN Q. SHERMAN. 

